I think interdiction should be a dice roll. It should take into account the NPC ship, the quality of their interdictor (make the range a static thing), and your ship/rank. Mix in a little RNG and it should either automatically fail or succeed depending on those factors. If it fails, have the interdictor "cool down" for that specific person for a set amount of time, and if it succeeds, well...pew pew.
Super easy: Take a D6 and roll it when interdicted. You can even design your own encounter random chance table to your very own liking and have it played out as you prefer. [up]